Visual-Manual NHTSA Driver Distraction Guidelines for In-Vehicle Electronic Devices
Notice Of Proposed Federal Guidelines.
The National Highway Traffic Safety Administration (NHTSA) is concerned about the effects of distraction due to drivers' use of electronic devices on motor vehicle safety. Consequently, NHTSA is issuing nonbinding, voluntary NHTSA Driver Distraction Guidelines (NHTSA Guidelines) to promote safety by discouraging the introduction of excessively distracting devices in vehicles.
This notice details the contents of the first phase of the NHTSA Driver Distraction Guidelines. These NHTSA Guidelines cover original equipment in-vehicle device secondary tasks (communications, entertainment, information gathering, and navigation tasks not required to drive are considered secondary tasks) performed by the driver through visual-manual means (meaning the driver looking at a device, manipulating a device-related control with the driver's hand, and watching for visual feedback).
The proposed NHTSA Guidelines list certain secondary, non-driving related tasks that, based on NHTSA's research, are believed by the agency to interfere inherently with a driver's ability to safely control the vehicle. The Guidelines recommend that those in-vehicle devices be designed so that they cannot be used by the driver to perform such tasks while the driver is driving. For all other secondary, non-driving-related visual-manual tasks, the NHTSA Guidelines specify a test method for measuring the impact of task performance on driving safety while driving and time-based acceptance criteria for assessing whether a task interferes too much with driver attention to be suitable to perform while driving. If a task does not meet the acceptance criteria, the NHTSA Guidelines recommend that in-vehicle devices be designed so that the task cannot be performed by the driver while driving. In addition to identifying inherently distracting tasks and providing a means for measuring and evaluating the level of distraction associated with other non-driving-related tasks, the NHTSA Guidelines contain several design recommendations for in-vehicle devices in order to minimize their potential for distraction.
NHTSA seeks comments on these NHTSA Guidelines and any suggestions for how to improve them so as to better enhance motor vehicle safety.
Table of Contents Back to Top
- FOR FURTHER INFORMATION CONTACT:
- SUPPLEMENTARY INFORMATION:
- Table of Contents
- I. Executive Summary
- A. The Problem of Driver Distraction and Related Research
- B. NHTSA Driver Distraction Program
- C. Today's Proposal
- II. Background
- A. Acronyms Used in Document
- B. The Driver Distraction Safety Problem
- i. Estimation of Distraction Crash Risk Via Naturalistic Driving Studies
- ii. Summary of Naturalistic Driving Study Distraction Risk Analyses
- C. NHTSA's Driver Distraction Program
- III. Why distraction guidelines?
- IV. NHTSA Research To Develop Driver Distraction Metrics and Measurement Methods
- A. Timeline of NHTSA Driver Distraction Measurement Research
- B. “15-Second Rule” Study
- C. Collision Avoidance Metrics Partnership (CAMP) Driver Workload Metrics Project 
- D. Measuring Distraction Potential of Operating In-Vehicle Devices 
- E. Developing a Test To Measure Distraction Potential of In-Vehicle Information System Tasks in Production Vehicles 
- F. Distraction Effects of Manual Number and Text Entry While Driving 
- G. Principal Findings of NHTSA Driver Distraction Metric Research
- V. Driver Distraction Prevention and Reduction Guidelines
- A. Currently Existing Driver Distraction Guidelines
- B. Why NHTSA Is Issuing Its Own Guidelines for Limiting and Reducing Driver Distraction
- C. First Phase of NHTSA's Driver Distraction Guidelines Focuses on Original Equipment Devices With Visual-Manual Driver Interfaces
- D. Past NHTSA Actions on Driver Distraction
- E. Challenges Relating to the Development of Interface Guidelines To Minimize Driver Distraction
- VI. Justification for Specific Portions of NHTSA Guidelines for Reducing Driver Distraction During Interactions With In-Vehicle Systems
- A. Intended Vehicle Types
- B. Existing Alliance Guidelines Provide a Starting Point
- C. International Harmonization and Voluntary Consensus Standards
- D. Statement of General Responsibilities
- E. Scope—Devices for Which the NHTSA Guidelines Are Appropriate
- F. Definition of a Task
- G. Definition of Lock Out
- H. Per Se Lock Outs
- I. Steering Wheel-Mounted Control Restrictions
- J. Maximum Downward Viewing Angle
- K. Tests Considered To Determine What Tasks Should Be Accessible While Driving
- L. NHTSA's Preferred Tests for Determining What Tasks Should Be Accessible While Driving
- M. Eye Glance Acceptance Criteria
- i. Selection of Manual Radio Tuning as the Reference Task
- ii. The Alliance Guidelines Acceptance Criteria
- iii. Recent NHTSA Research on Manual Radio Tuning
- iv. Development of NHTSA's Eye Glance Acceptance Criteria
- N. Human Subject Selection for Guideline Testing
- O. Occlusion Test Protocol
- P. Task Performance Errors During Testing
- Q. Limited NHTSA Guidelines for Passenger Operated Equipment
- VII. Implementation Considerations for the NHTSA Guidelines
- A. Current Vehicles That Meet the NHTSA Guidelines
- B. Expected Effects of the NHTSA Guidelines
- C. NHTSA Monitoring To Determine Whether Vehicles Meet Guideline Recommendations
- VIII. Public Participation
- How do I prepare and submit comments?
- How can I be sure that my comments were received?
- How do I submit confidential business information?
- Will the agency consider late comments?
- How can I read the comments submitted by other people?
- IX. National Technology Transfer and Advancement Act
- X. Guidelines for Reducing Visual-Manual Driver Distraction During Interactions With In-Vehicle Devices
- Option EGDS: Eye Glance Testing Using a Driving Simulator
- Option OCC: Occlusion Testing
- Option STEP: Step Counting
- Option DS-BM: Driving Test Protocol With Benchmark
- Option DS-FC: Driving Test Protocol With Fixed Acceptance Criteria
- Option DFD-BM: Dynamic Following and Detection Protocol With Benchmark
- Option DFD-FC: Dynamic Following and Detection Protocol With Fixed Acceptance Criteria
Tables Back to Top
- Table 1—Police-Reported Crashes and Crashes Involving Distraction, 2006-2010 (GES)
- Table 2—Matrix Showing NHTSA Driver Distraction Guideline Phases Based on Device Origins and Interaction Types
- Table 3—Summary of Distraction Test Protocols and Acceptance Criteria Considered by NHTSA
- Table 4—Estimated Number of Fatalities, Injuries, and Property Damage Only Crashes in 2009 Due to Radio, Cassette, or CD Player Use
- Table 5—Summary of Eye Glance Measures During the First Manual Radio Tuning Performed by Test Participants in a 2010 Toyota Prius on the NHTSA Driving Simulator (N = 90)
- Table 6—Summary of Eye Glance Measures During all Manual Radio Tuning Performed by Test Participants in a 2010 Toyota Prius on the NHTSA Driving Simulator (N = 541)
- Table 7—85th Percentiles of Eye Glance Measures During Manual Radio Tuning Trials Performed by in Various Vehicles Test Participants on the VTTI Smart Road (N = 228)
- Table 8—Percent of United States Drivers 18 Years of Age and Older in Each Age Range110
- Table 9—Types of Devices and Tasks for Which These Guidelines Are Appropriate
- Table 10—Summary of Distraction Test Protocols and Acceptance Criteria Considered by NHTSA
DATES: Back to Top
Comments: You should submit your comments early enough to ensure that the docket receives them not later than April 24, 2012.
Public Meetings: NHTSA will hold public meetings in March 2012 in three locations: Washington, DC; Los Angeles, California; and Chicago, Illinois. NHTSA will announce the exact dates and locations for each meeting in a supplemental Federal Register Notice.
ADDRESSES: Back to Top
You may submit comments to the docket number identified in the heading of this document by any of the following methods:
- Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the online instructions for submitting comments.
- Mail: Docket Management Facility: U.S. Department of Transportation, 1200 New Jersey Avenue SE., West Building Ground Floor, Room W12-140, Washington, DC 20590-0001
- Hand Delivery or Courier: 1200 New Jersey Avenue SE., West Building Ground Floor, Room W12-140, between 9 a.m. and 5 p.m. ET, Monday through Friday, except Federal holidays.
- Fax: 202-493-2251.
Instructions: For detailed instructions on submitting comments, see the Public Participation heading of the Supplementary Information section of this document. Note that all comments received will be posted without change to http://www.regulations.gov, including any personal information provided. Please see the “Privacy Act” heading below.
Privacy Act: Anyone is able to search the electronic form of all comments received into any of our dockets by the name of the individual submitting the comment (or signing the comment, if submitted on behalf of an association, business, labor union, etc.). You may review DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78) or you may visit http://DocketInfo.dot.gov.
Docket: For access to the docket to read background documents or comments received, go to http://www.regulations.gov or the street address listed above. Follow the online instructions for accessing the dockets.
FOR FURTHER INFORMATION CONTACT: Back to Top
For technical issues, you may contact Dr. W. Riley Garrott, Vehicle Research and Test Center, telephone: (937) 666-3312, facsimile: (937) 666-3590. You may send mail to this person at: The National Highway Traffic Safety Administration, Vehicle Research and Test Center, P.O. Box B-37, East Liberty, OH 43319.
SUPPLEMENTARY INFORMATION: Back to Top
These proposed NHTSA Guidelines will lead to issuance of final NHTSA Guidelines, which will not have the force and effect of law and will not be regulations. Therefore, NHTSA is not required to provide notice and an opportunity for comment. NHTSA is doing so, however, to ensure that its final NHTSA Guidelines benefit from the input of all knowledgeable and interested persons.
Table of Contents Back to Top
I. Executive Summary
A. The Problem of Driver Distraction and Related Research
B. NHTSA Driver Distraction Program
C. Today's Proposal
A. Acronyms Used in Document
B. The Driver Distraction Safety Problem
i. Estimation of Distraction Crash Risk Via Naturalistic Driving Studies
ii. Summary of Naturalistic Driving Study Distraction Risk Analyses
C. NHTSA's Driver Distraction Program
III. Why distraction guidelines?
IV. NHTSA Research To Develop Driver Distraction Metrics and Measurement Methods
A. Timeline of NHTSA Driver Distraction Measurement Research
B. “15-Second Rule” Study
C. Collision Avoidance Metrics Partnership (CAMP) Driver Workload Metrics Project
D. Measuring Distraction Potential of Operating In-Vehicle Devices
E. Developing a Test To Measure Distraction Potential of In-Vehicle Information System Tasks in Production Vehicles
F. Distraction Effects of Manual Number and Text Entry While Driving
G. Principal Findings of NHTSA Driver Distraction Metric Research
V. Driver Distraction Prevention and Reduction Guidelines
A. Currently Existing Driver Distraction Guidelines
B. Why NHTSA Is Issuing Its Own Guidelines for Limiting and Reducing Driver Distraction
C. First Phase of NHTSA's Driver Distraction Guidelines Focuses on Original Equipment Devices with Visual-Manual Driver Interfaces
D. Past NHTSA Actions on Driver Distraction
E. Challenges Relating to the Development of Interface Guidelines to Minimize Driver Distraction
VI. Justification for Specific Portions of NHTSA Guidelines for Reducing Driver Distraction During Interactions With In-Vehicle Systems
A. Intended Vehicle Types
B. Existing Alliance Guidelines Provide a Starting Point
C. International Harmonization and Voluntary Consensus Standards
D. Statement of General Responsibilities
E. Scope—Devices for Which the NHTSA Guidelines Are Appropriate
F. Definition of a Task
G. Definition of Lock Out
H. Per Se Lock Outs
I. Steering Wheel-Mounted Control Restrictions
J. Maximum Downward Viewing Angle
K. Tests Considered To Determine What Tasks Should Be Accessible While Driving
L. NHTSA's Preferred Tests for Determining What Tasks Should Be Accessible While Driving
M. Eye Glance Acceptance Criteria
i. Selection of Manual Radio Tuning as the Reference Task
ii. The Alliance Guidelines Acceptance Criteria
iii. Recent NHTSA Research on Manual Radio Tuning
iv. Development of NHTSA's Eye Glance Acceptance Criteria
N. Human Subject Selection for Guideline Testing
O. Occlusion Test Protocol
P. Task Performance Errors During Testing
Q. Limited NHTSA Guidelines for Passenger Operated Equipment
VII. Implementation Considerations for the NHTSA Guidelines
A. Current Vehicles That Meet the NHTSA Guidelines
B. Expected Effects of the NHTSA Guidelines
C. NHTSA Monitoring to Determine Whether Vehicles Meet Guideline Recommendations
VIII. Public Participation
IX. National Technology Transfer and Advancement Act
X. Guidelines for Reducing Visual-Manual Driver Distraction During Interactions with In-Vehicle Devices
I. Executive Summary Back to Top
A. The Problem of Driver Distraction and Related Research
The term “distraction,” as used in connection with these guidelines, is a specific type of inattention that occurs when drivers divert their attention away from the driving task to focus on another activity. These distractions can be from electronic devices, such as navigation systems and cell phones, or more conventional distractions such as interacting with passengers and eating. These distracting tasks can affect drivers in different ways, and can be categorized into the following types:
- Visual distraction: Tasks that require the driver to look away from the roadway to visually obtain information;
- Manual distraction: Tasks that require the driver to take a hand off the steering wheel and manipulate a device;
- Cognitive distraction: Tasks that require the driver to avert their mental attention away from the driving task.
The impact of distraction on driving is determined not just by the type of distraction, but also the frequency and duration of the task. That is to say, even if a task is less distracting, a driver who engages in it frequently or for long durations may increase the crash risk to a level comparable to that of much more difficult task performed less often.
NHTSA is concerned about the effects of driver distraction on motor vehicle safety. Crash data show that 17 percent (an estimated 899,000) of all police-reported crashes reportedly involved some type of driver distraction in 2010. Of those 899,000 crashes, distraction by a device/control integral to the vehicle was reported in 26,000 crashes (3% of the distraction-related police-reported crashes).
For a number of years, NHTSA has been conducting research to better understand how driver distraction impacts driving performance and safety. The research has involved both integrated and portable devices, various task types, and both visual-manual and auditory-vocal tasks (i.e., tasks that use voice inputs and provide auditory feedback). Additionally, both NHTSA and the Federal Motor Carrier Safety Administration (FMCSA) have sponsored analyses focused on distracted driving using data from naturalistic driving studies performed by the Virginia Tech Transportation Institute (VTTI).
The automobile industry, Europe, and Japan have all conducted valuable research that has increased the available knowledge regarding driver distraction and its effects on safety. The results of this work are summarized in various sets of guidelines that minimize the potential for driver distraction during visual-manual interactions while the vehicle is in motion. NHTSA has drawn heavily upon these existing guidelines in the development of its Driver Distraction Guidelines.
B. NHTSA Driver Distraction Program
In April 2010, NHTSA released an “Overview of the National Highway Traffic Safety Administration's Driver Distraction Program,”  which summarized steps that NHTSA intends to take to reduce crashes attributable to driver distraction. One part of this program is the development of nonbinding, voluntary guidelines for minimizing the distraction potential of in-vehicle and portable devices. The guidelines will be developed in three phases. The first phase will explore visual-manual interfaces of devices installed in vehicles. The second phase will include portable and aftermarket devices. The third phase will expand the guidelines to include auditory-vocal interfaces.
C. Today's Proposal
This notice proposes the first phase of these NHTSA Driver Distraction Guidelines, which cover certain devices installed in vehicles as original equipment that are operated by the driver through visual-manual means (meaning the driver looking at a device, manipulating a device-related control with the driver's hand, and watching for visual feedback from the device). The driver distraction research discussed above shows that the types of tasks correlated with the highest crash/near crash risk odds ratios tend to have primarily visual-manual means of interaction, and, accordingly, this first phase of guidelines focuses on visual-manual interfaces.
The purpose of the NHTSA Guidelines is to limit potential driver distraction associated with secondary, non-driving-related, visual-manual tasks (e.g., information, navigation, communications, and entertainment) performed using integrated electronic devices. The NHTSA Guidelines are not appropriate for conventional controls and displays (e.g., heating-ventilation-air conditions controls, instrument gauges or telltales) because operating these systems is part of the primary driving task. Likewise, the NHTSA Guidelines are not appropriate for collision warning or vehicle control systems, which are designed to aid the driver in controlling the vehicle and avoid crashes. These systems are meant to capture the driver's attention.
To facilitate the development of guidelines, NHTSA studied the various existing guidelines relating to driver distraction prevention and reduction and found the “Statement of Principles, Criteria and Verification Procedures on Driver-Interactions with Advanced In-Vehicle Information and Communication Systems” developed by the Alliance of Automobile Manufacturers (Alliance Guidelines  ) to be the most complete and up-to-date. The Alliance Guidelines provided valuable input in current NHTSA efforts to address driver distraction issues. While NHTSA drew heavily on that input in developing the NHTSA Guidelines, it did incorporate a number of changes in an effort to further enhance driving safety, enhance guideline usability, improve implementation consistency, and incorporate the latest driver distraction research findings.
Since light vehicles comprise the vast majority of the vehicle fleet, NHTSA focused its distraction research on this type of vehicle, instead of heavy trucks, medium trucks, motorcoaches, or motorcycles. Therefore, the NHTSA Guidelines contained in this notice cover light vehicles, i.e., all passenger cars, multipurpose passenger vehicles, and trucks and buses with a Gross Vehicle Weight Rating (GVWR) of not more than 10,000 pounds. While much of what NHTSA has learned about light vehicle driver distraction undoubtedly applies to other vehicle types, additional research would be desirable to assess whether all aspects of these NHTSA Guidelines are appropriate for those vehicle types.
The NHTSA Guidelines limit potential driver distraction associated with non-driving-related, visual-manual tasks through several approaches:
1. The NHTSA Guidelines list certain secondary, non-driving-related tasks that, based on NHTSA's research, are believed by the agency to interfere inherently with a driver's ability to safely control the vehicle. The Guidelines recommend that those in-vehicle devices be designed so that they cannot be used by the driver to perform such tasks while the driver is driving. The list of tasks considered to inherently interfere with a driver's ability to safely operate the vehicle include: displaying images or video not related to driving; displaying automatically scrolling text; requiring manual text entry of more than six button or key presses during a single task; or requiring reading more than 30 characters of text (not counting punctuation marks). The NHTSA Guidelines specify that this recommendation is intended to prevent the driver from engaging in tasks such as watching video footage, visual-manual text messaging, visual-manual internet browsing, or visual-manual social media browsing while driving. The recommendation is not intended to prevent the display of images related to driving, such as images related to the status of vehicle occupants or vehicle maneuvering or images depicting the rearview or blind zone areas of a vehicle.
2. For all other secondary, non-driving-related visual-manual tasks, the NHTSA Guidelines specify a test method for measuring the impact of performing a task on driving safety and time-based acceptance criteria for assessing whether a task interferes too much with driver attention to be suitable to perform while driving. If a task does not meet the acceptance criteria, the NHTSA Guidelines recommend that in-vehicle devices be designed so that the task cannot be performed by the driver while driving. More specifically, the NHTSA Guidelines include two test methods for assessing whether a task interferes too much with driver attention. One test method measures the amount of time that the driver's eyes are drawn away from the roadway during the performance of the task. The research mentioned above shows that long glances by the driver away from the roadway are correlated with an increased risk of a crash or near-crash. The NHTSA Guidelines recommend that devices be designed so that tasks can be completed by the driver while driving with glances away from the roadway of 2 seconds or less and a cumulative time spent glancing away from the roadway of 12 seconds or less. The second test method uses a visual occlusion technique to ensure that a driver can complete a task in a series of 1.5 second glances with a cumulative time spent glancing away from the roadway of not more than 9 seconds.
3. In addition to identifying inherently distracting tasks and providing a means for measuring and evaluating the level of distraction associated with other non-driving-related tasks, the NHTSA Guidelines contain several design recommendations for in-vehicle devices in order to minimize their potential for distraction. The NHTSA Guidelines recommend that all device functions designed to be performed by the driver through visual-manual means should require no more than one of the driver's hands to operate. The NHTSA Guidelines further recommend that each device's active display should be located as close as practicable to the driver's forward line of sight and include a specific recommendation for the maximum downward viewing angle to the geometric center of each display.
The agency believes that the NHTSA Guidelines are appropriate for any device that the driver can easily see and/or reach (even if it is intended for use solely by passengers), and, accordingly, any task that is associated with an unacceptable level of distraction should be made inaccessible to the driver while driving. However, the NHTSA Guidelines are not appropriate for any device that is located fully behind the front seat of the vehicle or for any front-seat device that cannot reasonably be reached or seen by the driver.
NHTSA has opted to pursue nonbinding, voluntary guidelines rather than a mandatory Federal Motor Vehicle Safety Standard (FMVSS) for three principal reasons. First, this is an area in which learning continues, and NHTSA believes that, at this time, continued research is both necessary and important. Second, technology is changing rapidly, and a static rule, put in place at this time, may face unforeseen problems and issues as new technologies are developed and introduced. Third, available data are not sufficient at this time to permit accurate estimation of the benefits and costs of a mandatory rule in this area. NHTSA's firm belief that there are safety benefits to be gained by limiting and reducing driver distraction due to integrated electronic devices is sufficient reason for issuing the NHTSA Guidelines, but in order to issue a rule, we need a defensible estimate of the magnitude of such benefits and the corresponding costs. (See Executive Order 13563.)
Since these voluntary NHTSA Guidelines are not a FMVSS, NHTSA's normal enforcement procedures are not applicable. As part of its continuing research effort, NHTSA does intend to monitor manufacturers' voluntary adoption of these NHTSA Guidelines to help determine their effectiveness and sufficiency.
The main effect that NHTSA expects to achieve through its NHTSA Guidelines is better-designed in-vehicle integrated electronic device interfaces that do not exceed a reasonable level of complexity for visual-manual secondary tasks. While voluntary and nonbinding, the NHTSA Guidelines are meant to discourage the introduction of egregiously distracting non-driving tasks performed using integrated devices (i.e., those that the NHTSA Guidelines list as being inherently distracting and those that do not meet the acceptance criteria when tested under the test method contained in the Guidelines).
NHTSA seeks comments as to how to improve the NHTSA Guidelines so as to improve motor vehicle safety. Because these Guidelines are voluntary and nonbinding, they will not require action of any kind, and for that reason they will not confer benefits or impose costs. Nonetheless, and as part of its continuing research efforts, NHTSA welcomes comments on the potential benefits and costs that would result from voluntary compliance with the draft Guidelines.
NHTSA will review submitted comments and plans to issue a final version of the visual-manual portion of its NHTSA Guidelines in the form of a Federal Register notice during the first half of calendar year 2012.
II. Background Back to Top
A. Acronyms Used in Document
ADAMAdvanced Driver Attention Metrics
ANPRMAdvance Notice of Proposed Rulemaking
CAMPCollision Avoidance Metrics Partnership
CANbusController Area Network bus
CDSCrashworthiness Data System (NASS-CDS)
DFDDynamic Following and Detection
DOTDepartment of Transportation
EOTEnhanced Occlusion Technique
FARSFatality Analysis Reporting System
FMCSAFederal Motor Carrier Safety Administration
FMVSSFederal Motor Vehicle Safety Standard
GESGeneral Estimates System (NASS-GES)
GVWRGross Vehicle Weight Rating
HVACHeating, Ventilation, and Air Conditioning
ISOInternational Standards Organization
ISOESInternational Society for Occupational Ergonomics and Safety
IVISIn-Vehicle Information Systems
JAMAJapanese Automobile Manufacturers Association
LCTLane Change Task
MGDMean Glance Duration
MNTEManual Number and Text Entry
NASSNational Automotive Sampling System
NHTSANational Highway Traffic Safety Administration
NMVCCSNational Motor Vehicle Crash Causation Survey
NPRMNotice of Proposed Rulemaking
NTTAANational Technology Transfer and Advancement Act
OMBOffice of Management and Budget
PARPolice Accident Report
PDTPeripheral Detection Task
RTask Resumability Ratio
SDLPStandard Deviation of Lane Position (lane position variability)
SHRP2Strategic Highway Research Program 2
STISystems Technology Incorporated
STISIMSystems Technology Incorporated Driving Simulator
TEORTTotal Eyes-Off-Road Time
TGTTotal Glance Time to Task
VTTIVirginia Tech Transportation Institute
B. The Driver Distraction Safety Problem
There has been a large amount of research performed on the topic of driver distraction and its impact on safety. Research noted here will provide a brief overview of the distraction safety problem. Many other reports and papers have been published on various aspects of driver distraction. Some of these additional reports and papers may be found at www.distraction.gov.
NHTSA data on distracted driving-related crashes and the resulting numbers of injured people and fatalities is derived from the Fatality Analysis Reporting System (FARS)  and the National Automotive Sampling System (NASS) General Estimates System (GES). 
The most recent data available, 2010 data, show that 17 percent of all police-reported crashes (fatal, injury-only and property-damage-only) involve reports of distracted driving. As can be seen in Table 1, the percent of all police-reported crashes that involve distraction has remained consistent over the past five years. These distraction-related crashes lead to thousands of fatalities and over 400,000 injured people each year, on average.
An estimated 899,000 of all police-reported crashes involved a report of a distracted driver in 2010. Of those 899,000 crashes, 26,000 (3%) specifically stated that the driver was distracted when he was adjusting or using an integrated device/control. From a different viewpoint, of those 899,000 crashes, 47,000 (5%) specifically stated that the driver was distracted by a cell phone (no differentiation between portable and integrated). It should be noted that these two classifications are not mutually exclusive, as a driver who was distracted by the radio control may have also been on the phone at the time of the crash and thus the crash may appear in both categories. While all electronic devices are of interest, the current coding does not separate other electronic devices other than cell phones.
|Year||Number of police-reported crashes||Police-reported crashes involving a distracted driver||Distraction-related crashes involving an integrated control/device*||Distraction-related crashes involving an electronic device*|
|*The categories for Integrated Control/Device and Electronic Device are not mutually exclusive. Therefore the data cannot be added or combined in any manner.|
|2006||5,964,000||1,019,000 (17%)||18,000 (2%)||24,000 (2%)|
|2007||6,016,000||1,001,000 (17%)||23,000 (2%)||48,000 (5%)|
|2008||5,801,000||967,000 (17%)||21,000 (2%)||48,000 (5%)|
|2009||5,498,000||957,000 (17%)||22,000 (2%)||46,000 (5%)|
|2010||5,409,000||899,000 (17%)||26,000 (3%)||47,000 (5%)|
Identification of specific driver-activities and driver-behavior that serves as the distraction has presented challenges, both within NHTSA's data collection and on police accident reports. Therefore, a large portion of the crashes that are reported to involve distraction do not have a specific behavior or activity listed; rather they specify other distraction or distraction unknown. One could assume that some portion of those crashes involve an electronic device, either portable or integrated.
NHTSA is making substantial data collection revisions to FARS and working on revisions to Model Minimum Uniform Crash Criteria (MMUCC) to better capture and classify the crashes related to distraction.  One such improvement is the ability to separate the involvement of integrated vehicle equipment as the distraction in fatal crashes in FARS. With this improvement, NHTSA looks to track the involvement of integrated devices over time in fatal crashes. As manufacturers are increasingly developing communications systems that can integrate portable devices into the vehicle or developing fully-integrated systems in the vehicle, this tracking of data will be essential in monitoring distraction involvement in fatal crashes.
i. Estimation of Distraction Crash Risk Via Naturalistic Driving Studies
One approach to estimating the driving risks due to various types of distraction is naturalistic driving studies. Naturalistic data collection is an excellent method of determining distraction risks because test participants (drivers) volunteer to drive an instrumented vehicle in the same manner that they normally do for some period of time. Unlike commanded task testing, in which an in-vehicle experimenter instructs a test participant when to perform a task, in naturalistic studies test participants perform tasks at will. The unobtrusive data recording instrumentation installed in the vehicle eliminates the distraction under-reporting problem seen in police accident reports by recording data that describes what test participants are doing at any time while driving.
For light vehicles, the NHTSA-sponsored 100-Car Naturalistic Driving Study, 6 7 8 9 10 performed by the Virginia Tech Transportation Institute (VTTI), provides information about the effects of performing various types of secondary tasks on crash/near crash risks. Secondary tasks include communications, entertainment, informational, interactions with passengers, navigation, and reaching for objects tasks (along with many others) that are not required for driving. For the 100-Car Study, VTTI collected naturalistic driving data for 100 vehicles from January 2003 through July 2004. Each participant's vehicle was unobtrusively fitted with five video cameras, sensors that measured numerous vehicle state and kinematic variables at each instant of time, and data acquisition. The vehicles were then driven by their owners during their normal daily activities for 12 to 13 months while data were recorded. No special instructions were given to drivers as to when or where to drive and no experimenter was present in the vehicle during the driving. All of this resulted in a large data set of naturalistic driving data that contains information on 241 drivers (100 primary drivers who performed most of the driving and 141 secondary drivers who drove the instrumented vehicles for shorter periods of time) driving for almost 43,000 hours and traveling approximately 2 million miles.
Data from the 100-Car Naturalistic Driving Study provides the best information currently available about the risks associated with performing a variety of secondary tasks while driving light vehicles (vehicles under 10,000 pounds GVWR). However, even though this was a large, difficult, and expensive study to perform, from an epidemiological viewpoint, the study was small (100 primary drivers, 15 police-reported and 82 total crashes, including minor collisions). Drivers from only one small portion of the country, the Northern Virginia-Washington, DC, metro area, were represented.
The 100-Car Study was deliberately designed to maximize the number of crash and near-crash events through the selection of subjects with higher than average crash- or near-crash risk exposure.  This was accomplished through the selection of a larger sample of drivers below the age of 25, and by the inclusion of a sample that drove more than the average number of miles.
Due to the rapid pace of technological change, some devices (e.g., smart phones) and secondary tasks of great current interest (e.g., text messaging) were not addressed by 100-Car Study data because they were not widely in use at the time.
Subsequent to the 100-Car Naturalistic Driving Study, the Federal Motor Carrier Safety Administration (FMCSA) sponsored an analysis of naturalistic driving data  to examine the effects of driver distraction on safety for commercial motor vehicles (three or more axle trucks, tractors-semitrailers (including tankers), transit buses, and motor coaches). This analysis used data collected during two commercial motor vehicle naturalistic driving studies. Since the data analyzed was collected during two studies, this study will, hereinafter, be referred to as the “Two Study FMCSA Analyses.”
The Two Study FMCSA Analyses combined and analyzed data from two large-scale commercial motor vehicle naturalistic driving studies: the Drowsy Driver Warning System Field Operational Test  and the Naturalistic Truck Driving Study.  The combined database contains naturalistic driving data for 203 commercial motor vehicle drivers, 7 trucking fleets, 16 fleet locations, and approximately 3 million miles of continuously-collected kinematic and video data. This data set was filtered using kinematic data thresholds, along with video review and validation, to find safety-critical events (defined in this report as crashes, near-crashes, crash-relevant conflicts, and unintentional lane deviations). There were a total of 4,452 safety-critical events in the database: 21 crashes, 197 near-crashes, 3,019 crash-relevant conflicts, and 1,215 unintentional lane deviations. In addition, 19,888 time segments of baseline driving data were randomly selected for analysis.
One major source of differences in the results obtained from analyses of the 100-Car Study with those obtained from the Two Study FMCSA Analyses is the different time frames in which their data collections were performed. The 100-Car Naturalistic Driving Study data collection was from January 2003 through July 2004. The Drowsy Driver Warning System Field Operational Test collected data from May 2004 through September 2005 and the Naturalistic Truck Driving Study collected data from November 2005 through May 2007. Due to the current rapid changes occurring in portable and other consumer electronics, the specific types of electronic device related distraction observed across studies, while similar, were not identical. For example, while the Two Study FMCSA Analyses found a high safety critical event risk due to drivers engaging in text messaging, there was no text messaging observed during the 100-Car Study. This is because the widespread popularity of text messaging did not occur until after the 100-Car Study data collection was completed.
ii. Summary of Naturalistic Driving Study Distraction Risk Analyses
Figure 1 gives a graphical representation of some of the secondary task risk odds ratios determined by the 100-Car Naturalistic Driving Study and the Two Study FMCSA Analyses. In this figure, a risk odds ratio of 1.00 (shown as “1” in the figure) equates to the risks associated with baseline driving. Risk odds ratios above 1.00 indicate secondary tasks that increase driving risks while risk odds ratios below 1.00 indicate protective effects (i.e., performing these secondary tasks makes a crash or near-crash event less likely to occur than driving and not performing any secondary task.) This figure provides a quick, visual, summary of the risks associated with performing a variety of secondary tasks while driving both light and heavy vehicles.
In summary, the various naturalistic data study analyses established several important things about driver distraction which are directly relevant to the NHTSA Guidelines for reducing driver distraction due to device interface design:
- Secondary task performance is very common while driving. They were observed during the majority (54%) of the randomly selected baseline time segments analyzed during the 100-Car Study analyses. Some secondary task performance involves the use of electronic devices; these secondary tasks are the primary focus of this document.
- Secondary task performance while driving has a broad range of risk odds ratios associated with different secondary tasks. The observed risk odds ratios range from 23.2, indicating a very large increase in crash/near-crash risk (a risk ratio of 1.0 means that a secondary task has the same risk as average driving; a risk ratio of 23.2 means that risk associated with performance of this secondary task is increased by 2,220 percent compared to average driving), to 0.4 (any value less than 1.0 indicates a situation with less risk than average driving indicating a protective effect; a risk ratio of 0.4 means that risk associated with performance of this secondary task is reduced by 60 percent compared to average driving). This indicates that it may well be possible to improve at least some of the secondary tasks with high risk odds ratios (i.e., risky tasks) so as to make them substantially safer to perform. The logical place to reduce crash/near-crash risk odds ratios for these secondary tasks is through improvements to their driver interface.
- It is clear from naturalistic driving research that the secondary tasks with the highest risk odds ratios tend to have primarily visual-manual interaction means with only a relatively small cognitive component. Of course, every secondary task results in some cognitive load; however, tasks that could be said to not require a lot of thought, such as Reaching for a Moving Object, are towards the right side of Figure 1. Only the secondary tasks, “Interacting with Passenger” and “Talking/Listening on Hands-Free Phone,” are almost exclusively cognitive in nature. Both of these secondary tasks have risk odds ratios that are statistically significantly less than 1.00 (at the 95 percent confidence level). These two heavily cognitive secondary tasks appear to have protective effects.
For this reason, and because it is far less clear how to measure the level of cognitive distraction, the NHTSA Guidelines will initially only apply to the visual-manual aspects of devices' driver interfaces. Subsequent phases of development of these NHTSA Guidelines are planned to extend them to cover the auditory-vocal portions of device interfaces.
- Long (greater than 2.0 seconds) glances by the driver away from the forward road scene are correlated with increased crash/near-crash risk. When drivers glance away from the forward roadway for greater than 2.0 seconds out of a 6-second period, their risk of an unsafe event substantially increases relative to the baseline.
C. NHTSA's Driver Distraction Program
NHTSA's safety mission is to “save lives, prevent injuries, and reduce economic costs due to road traffic crashes.” One focus of this mission is the prevention of road traffic crashes for which driver distraction is a contributing factor. 
In April 2010, NHTSA released an “Overview of the National Highway Traffic Safety Administration's Driver Distraction Program,”  which summarized steps that NHTSA intends to take to “help in its long-term goal of eliminating a specific category of crashes—those attributable to driver distraction.” NHTSA's Driver Distraction Program consists of four initiatives:
1. Improve the understanding of the extent and nature of the distraction problem. This includes improving the quality of data NHTSA collects about distraction-related crashes along with better analysis techniques.
2. Reduce the driver workload associated with performing tasks using both built-in and portable in-vehicle devices by working to limit the visual and manual demand associated with secondary tasks performed using in-vehicle devices. Better device interfaces will help to minimize the amount of time and effort involved in a driver performing a task using the device. Minimizing the workload associated with performing non-driving, or “secondary,” tasks with a device will permit drivers to maximize the attention they focus toward the primary task of driving.
3. Keep drivers safe through the introduction of crash avoidance technologies. These include the use of crash warning systems to re-focus the attention of distracted drivers as well as vehicle-initiated (i.e., automatic) braking and steering to prevent or mitigate distracted driver crashes.
Although not the focus of this notice, NHTSA is, in parallel with its NHTSA Guidelines development effort, performing a large amount of research in support of the crash avoidance technologies initiative. For example, NHTSA has completed, and reports should be published shortly, research about how to best warn distracted drivers. We are also performing a large amount of research on forward collision avoidance and mitigation technologies such as Forward Collision Warning, Collision Imminent Braking, and Dynamic Brake Assist.
4. Educate drivers about the risks and consequences of distracted driving. This includes targeted media messages, drafting and publishing sample text-messaging laws for consideration and possible use by the states, and publishing guidance for a ban on text messaging by Federal government employees while driving.
This notice is part of NHTSA's effort to address the second of these initiatives, reducing driver workload by working to limit the visual and manual demand associated with in-vehicle device interface designs. As discussed in NHTSA's Driver Distraction Program, NHTSA's intent is to “develop voluntary guidelines for minimizing the distraction potential of in-vehicle and portable devices”.  The current notice only contains voluntary NHTSA Guidelines for integrated in-vehicle devices; portable devices will be addressed by Phase 2 of the NHTSA Guidelines.
Drivers perform secondary tasks (communications, entertainment, informational, and navigation tasks not required to drive  ) using an in-vehicle electronic device by interacting with the device through its driver interface. These interfaces can be designed to accommodate interactions that are visual-manual (visual display and manual controls), auditory-vocal, or a combination of the two. Some devices may allow a driver to perform a task through either manual control manipulation with visual feedback or through voice command with auditory feedback to the driver.
For the purposes of this document, a driver's interactions with device interfaces are described in terms of two functional categories based upon the mode of interaction: visual-manual and auditory-vocal. Visual-manual interactions involve the driver looking at a device, making inputs to the device by hand (e.g., pressing a button, rotating a knob), and visual feedback being provided to the driver. Auditory-vocal interactions involve the driver controlling the device functions through voice commands and receiving auditory feedback from the device. Note that a single device's driver interface may accommodate both visual-manual and auditory-vocal interactions.
These proposed voluntary NHTSA Guidelines are appropriate for in-vehicle device tasks that are performed by the driver through visual-manual means. The goal of the NHTSA Guidelines is to discourage the implementation of tasks performed using in-vehicle electronic devices unless the tasks and device driver interfaces are designed to minimize driver workload experienced by a driver when performing the tasks while driving. The NHTSA Guidelines specify criteria and a test method for assessing whether a secondary task performed using an in-vehicle device may be suitable for performance while driving, due to its minimal impact on driving performance and, therefore, safety. The NHTSA Guidelines also seek to identify secondary tasks that interfere with a driver's ability to safely control the vehicle and to categorize those tasks as being unsuitable for performance by the driver while driving.
III. Why distraction guidelines? Back to Top
NHTSA is proposing voluntary NHTSA Guidelines to limit and/or reduce visual-manual driver distraction due to integrated electronic devices, instead of a mandatory Federal Motor Vehicle Safety Standard (FMVSS), for several reasons. First, the rapid pace of technology evolution cannot be fully addressed with a static rule put in place at this time. Second, data is not sufficient at this time to permit accurate estimation of the benefits of a possible distracted driving rule, though NHTSA firmly believes that there are safety benefits to be gained by limiting and reducing driver distraction due to integrated electronic devices. Finally, NHTSA rules must have repeatable, objective means for determining compliance and driver distraction testing involves drivers with inherent individual differences that present a unique challenge. Each of these reasons is discussed in detail below.
- In 2002, the Alliance of Automobile Manufacturers developed a set of guidelines to address the agency's call that manufacturers should develop a set of design principles to which future products would be designed. The intent was to address the increasing use of navigation units, infotainment, and complex controls appearing in vehicles that, if used while driving, could present an additional source of distraction for drivers leading to an increase in crashes. Since that time, NHTSA has been monitoring and conducting driver distraction research using a sample of the designs that have been developed in accordance with the Alliance Guidelines. Our observations are as follows: (1) Manufacturers have different interpretations of the guidelines themselves, leading to different implementations, (2) newer techniques exist to evaluate these interfaces than existed nearly a decade ago, (3) the guidelines have not kept pace with technology, and (4) more recent data compiled from naturalistic driving studies implies that more stringent criteria are needed. Given these observations, we believe it is appropriate to issue Federal guidelines to ensure that current and future products continue to be designed in such a way as to mitigate driver distraction as opposed to adding to it. In addition, we believe Federal guidelines are appropriate because they can keep pace with rapidly changing technology by providing a benchmark for designers while allowing the agency and other researchers to continue their work in this rapidly evolving area, including the assessment of test procedures for regulatory purposes.
- In-vehicle communications and electronics are currently evolving at a pace that is not amenable to regulation. We believe that establishing Federal guidelines at this time is appropriate for these rapidly changing in-vehicle technologies, since it will provide a comprehensive means to ensure the reasonableness of designs. As new systems, features, functions, and types of control inputs are developed, NHTSA should be able to develop voluntary NHTSA Guidelines to address any potential safety issues as they arise. These NHTSA Guidelines can be issued more quickly than regulations that go through the rulemaking process.
- Existing data provide a sufficient basis on which to establish general NHTSA Guidelines that, if followed, will deter manufacturers from introducing in-vehicle information and communications systems that induce the kinds and duration of visual-manual distraction that are demonstrably unsafe. In future years, data from a major naturalistic research study that is currently being conducted through the Strategic Highway Research Program 2 (SHRP2)  should provide better information on the precise causation of distraction related incidents.
- Additionally, the test method developed by NHTSA in these NHTSA Guidelines in its current form would not meet the statutory requirements for establishing compliance with a FMVSS. Specifically, NHTSA's authorizing legislation requires that FMVSS contain objective and repeatable procedures, such as engineering measurement, for determining compliance or non-compliance of a vehicle with the standard. Driver distraction testing involves human drivers with inherent individual differences that present a unique challenge. A FMVSS with a compliance test procedure that entails driver involvement would not meet those requirements due to the individual variability of the drivers involved in the test.
Consider a brake compliance test; it tests the manufactured parts that comprise the braking, wheel, and tire systems. NHTSA has gone to considerable effort to tightly prescribe the actions of the professional test driver so that they do not influence test results. The main sources of test non-repeatability are the manufacturing tolerances of the vehicle components and the variability in the road surface. Again, NHTSA has tried to specify the road surface so as to minimize test variability. Due to the tight specification of test driver's actions and road surface, brake compliance testing is highly repeatable.
In comparison, driver distraction tests involve average drivers as a critical part of the test of the in-vehicle system. The driver's actions cannot be tightly prescribed, as was done for brake testing. Unfortunately, the level of driver distraction due to performing a task using a device inherently depends upon the personal characteristics and capabilities of the driver. The driver's manual dexterity, multi-tasking ability, driving experience, state of health, age, intelligence, and motivation (among other factors) may all influence the level of distraction experienced while performing a task. In an effort to “average out” individual differences, a group of 24 test participants is used for the NHTSA Driver Distraction Guideline tests described in this document. Furthermore, these NHTSA Guidelines contain provisions designed to ensure that test participants are not biased either for or against a task/device. However, there remains a chance that one group of 24 test subjects will produce a test result that finds a task or device suitable for performance while the vehicle is in motion, while testing with another group of 24 subjects may find that the task or device should be locked out. Therefore, the test would not be repeatable and therefore is not appropriate for a FMVSS. 
IV. NHTSA Research To Develop Driver Distraction Metrics and Measurement Methods Back to Top
A. Timeline of NHTSA Driver Distraction Measurement Research
NHTSA has been performing research addressing issues related to driver distraction for nearly 20 years. Early research examined truck driver workload and the effects of using a route navigation system on driving performance. In the last decade, research has been focused on assessing the impact of cell phone use on driver performance and behavior. As the availability of in-vehicle electronic devices has increased, NHTSA's research focus has shifted to development of methods and metrics for measuring distraction resulting from the use of any such device while driving. Each research study has contributed to the development of a broad set of metrics that characterize the impact of the performance of distracting tasks on driving performance in a repeatable and objective manner. The development of valid and sensitive measures of distraction effects on driving performance is challenging because distraction measurement inherently involves human test subjects. This section summarizes several recent NHTSA studies that focused on developing a valid, robust protocol for measuring driver distraction caused by the use of in-vehicle electronic devices.
B. “15-Second Rule” Study
In the 1990s, SAE International worked to develop a recommended practice for determining whether or not a particular navigation system function should be accessible to the driver while driving. The draft recommended practice (SAE J2364) 21 22 asserted that if an in-vehicle task could be completed within 15 seconds by a sample of drivers in a static (e.g., vehicle parked) setting, then the function was suitable to perform while driving. NHTSA conducted a preliminary assessment of the diagnostic properties of this proposed rule. Ten subjects, aged 55 to 69 years, completed 15 tasks, including navigation system destination entry, radio tuning, manual phone dialing, and adjusting the Heating, Ventilation, and Air Conditioning (HVAC) controls in a test vehicle. Correlations between static task performance and dynamic task performance were relatively low. The results were interpreted to suggest that static measurement of task completion time could not reliably predict the acceptability of a device. Based on these results, NHTSA looked to other metrics and methods for use in assessing secondary task distraction in subsequent research.
C. Collision Avoidance Metrics Partnership (CAMP) Driver Workload Metrics Project 
The Driver Workload Metrics project conducted by the Collision Avoidance Metrics Partnership (CAMP) consortium,  in cooperation with NHTSA, sought to develop performance metrics and test procedures for assessing in-vehicle system secondary task distraction and its impact on driving performance. The CAMP identified four categories of driving performance metrics as having direct implications for safety: driver eye glance patterns, lateral vehicle control, longitudinal vehicle control, and object-and-event detection. A number of potential surrogates thought to have predictive value with respect to the above-mentioned performance measures were identified. CAMP's analyses sought to determine which performance metrics discriminated between driving with a secondary task and driving alone. The majority of metrics that passed the evaluation criteria were related to eye-glance behavior. Visual-manual tasks affected driving performance more than auditory-vocal tasks. The project concluded that eye-glance data contain important information for assessing the distraction effects of both auditory-vocal and visual-manual tasks. One significant conclusion of this work was that the interference to driving caused by in-vehicle secondary tasks was multidimensional and no single metric could measure all effects.
D. Measuring Distraction Potential of Operating In-Vehicle Devices 
Following the Driver Workload Metrics project, in 2006, NHTSA explored the feasibility of adapting one or more existing driver distraction measurement protocols for use with production vehicles rather than pre-production prototypes. NHTSA wanted a well-documented, simple, non-destructive test that would allow test vehicles to be obtained by lease and therefore minimize research costs. Additional protocol criteria included: (1) Ease of implementation, (2) the test protocol's state-of-development, including extent of use and documentation, (3) the level of training and staffing required, (4) objective measures, and (5) the availability and interpretability of data.
Test venues meeting these criteria included the personal computer-based Advanced Driver Attention Metrics (ADAM) Lane Change Task (LCT)  and the Systems Technology Inc. (STI) low-cost, low-fidelity driving simulator (STISIM-Drive). The LCT is a standalone driving simulation that requires drivers to execute lane changes when prompted by signs appearing in the scenario. The LCT combines vehicle control performance, object detection, and response speed into a single summary performance measure. Based on CAMP  study recommendations, the STISIM driving scenario used involved car following with occasional oncoming traffic, in combination with the Peripheral Detection Task (PDT) to provide a visual object-event detection component. A Seeing Machines faceLab eye tracking system was used with both primary test venues.
Two initial experiments were conducted to evaluate the metrics associated with the STISIM and LCT test venues and to assess the metrics' sensitivity for detecting known and hypothesized differences between different secondary tasks. Results showed that most metrics were sensitive to changes in visual-manual load associated with visual search tasks. STISIM driving performance and PDT metrics were the most sensitive objective metrics and were generally more sensitive than LCT metrics. A third experiment that compared the sensitivity of measures obtained in the laboratory with that of an established test track protocol showed similarity among patterns of workload ratings. However, the laboratory simulator measures were more sensitive to secondary task load differences than the corresponding test track measures.
Overall, the laboratory environment provided better control of test conditions, particularly visibility, and less measurement error than the test track. The limited fidelity of the simulator did not reduce the sensitivity of the simulator-based metrics for detecting the targeted differences between task conditions. The breadth of STISIM/PDT measurement capabilities is also consistent with the general consensus that multiple measures are necessary to fully characterize distraction effects. Thus, the driving simulator protocol was retained for further research.
E. Developing a Test To Measure Distraction Potential of In-Vehicle Information System Tasks in Production Vehicles 
In 2009, NHTSA continued its efforts to develop a sensitive method of driver distraction measurement using production vehicles. Research was conducted using the visual occlusion technique, which involves periodic interruption of vision (via electronically shuttered goggles or some other apparatus) during the performance of a secondary task to simulate the driver glancing at the roadway while driving. By summing the duration of periods of unoccluded vision, the technique provides an estimate of the time that the driver looks away from the roadway to perform the secondary task. Because in the traditional occlusion method, participants have no primary task load (to simulate the demands of driving), the task completion time estimates do not include time during which participants continue to work on the secondary task during occluded intervals. To address this “blind operation” concern, an Enhanced Occlusion Technique (EOT) was also examined. This technique incorporated an auditory tracking task intended to simulate the demands of driving without interfering with the visual demands of occlusion.
The study compared task completion times obtained with the traditional occlusion protocol with those obtained using the EOT to assess their relative abilities to assess the distraction effects of secondary tasks. The experiment also sought to determine the extent to which blind operation is eliminated by the EOT. Data from occlusion trials were also used to compute indices of task resumability (R), which indicate how amenable a task is to completion under conditions of interruption, as in driving. Three navigation system tasks were used, including destination entry by address, selecting a previous destination, and searching a list of cities. Results showed that the EOT eliminated some blind operation, but not all of it. Specifically, with traditional occlusion, approximately 23 percent of the actions required to perform the task was accomplished during occluded intervals. With the EOT, the corresponding percentage was 11 percent. The R metrics differed between the traditional occlusion and EOT conditions, but neither R metric revealed differences between secondary task conditions. This led to the conclusion that task resumability (R) does not reflect the same performance degradation revealed by the driving performance metrics. The destination entry by address task was associated with a significantly higher level of (auditory) tracking error than the previous destination task.
A complementary experiment was conducted as part of this project using a multiple-target detection task to assess the distraction potential of three navigation systems with comparable functionality. Participants performed two navigation system tasks (destination entry by address and previous destination) using one original equipment system and two portable systems, each differing in their rated usability. Metrics revealed strong and consistent differences between baseline driving and driving with a secondary task. Three objective metrics (car-following coherence, detection task mean response time and the proportion of long glances) revealed differences between the destination entry by address and previous destination tasks generally. Based on the results of these experiments, it was concluded that it is feasible to use a simulator-based test to assess the distraction potential of secondary tasks performed with original equipment systems integrated into production vehicles. Test results indicated that a broad range of metrics, including measures of car-following, lateral vehicle control, target detection, and visual performance, were consistently and robustly sensitive to differences between categories of secondary tasks and between baseline driving and driving while performing secondary tasks. Fewer metrics were found to be sensitive to differences between visual-manual task conditions: Lane-position variability (SDLP), the time required for a following vehicle to react to lead vehicle speed changes, and detection task response time.
While the EOT represented an improvement over the traditional occlusion paradigm for providing information about the time required to perform various secondary tasks, task duration estimates obtained with either the traditional occlusion protocol or the EOT both differed from comparable values obtained in a controlled driving situation. Due to their increased sensitivity for detecting differences within task conditions, the SDLP, the time required for a following vehicle to react to lead vehicle speed changes, detection task response time and proportion of correct responses are considered core metrics for assessing distraction potential using driving simulation methods. Measures based on eye position data, primarily the proportion of long glances away from the forward roadway, also exhibited differences between tasks.
F. Distraction Effects of Manual Number and Text Entry While Driving 
In 2010, NHTSA conducted research to further develop its driving simulator method in order to assess the distraction potential of secondary tasks performed using in-vehicle information systems in production vehicles or portable electronic devices. The “Dynamic Following and Detection” (DFD) method combines car following and visual target detection, can be used with different vehicles, and requires minimal set up effort. Performance degradation in measures of lateral position, car following, and visual target detection, which are recorded for trials with secondary tasks, is compared to baseline driving performance and trials with a benchmark task (destination entry). NHTSA conducted a study to assess the effects of performing Manual Number and Text Entry (MNTE) tasks using integrated and portable devices in a driving simulator scenario to compare the DFD metrics with metrics specified in the Alliance of Automobile Manufacturers Driver-Focus Telematics Guidelines (the Alliance Guidelines). This study was also intended to evaluate different test participant selection criteria and sample sizes.
Specifically, the study examined Alliance Guidelines' Principle 2.1, which states:
Systems with visual displays should be designed such that the driver can complete the desired task with sequential glances that are brief enough not to adversely affect driving. 
The Alliance proposed two alternatives for assessing compliance. Alternative A includes two criteria that should be met: (1) durations of single glances to the task should generally not exceed 2 seconds; and (2) total glance time to the task (TGT) should not exceed 20 seconds. Alternative B identifies two driving performance measures (lane exceedance frequency and car-following headway variability) and outlines a generic test protocol in which task-related degradation is related to degradation on a benchmark task (radio tuning).
For the MNTE study, an experiment was conducted in which 100 participants aged 25 to 64 years performed number and text entry tasks during 3-minute drives using the STISIM driving simulator. Sensors connected to the steering, brake, and throttle of a single stationary 2010 Toyota Prius (with engine off) provided control inputs to the fixed-base driving simulator. The significant overlap in data collection requirements between Alliance and DFD protocols allowed the necessary data for a side-by-side comparison to be obtained from a single experiment. The experiment had three independent variables: (1) Portable device (hard button cell phone or touch-screen cell phone)  ; (2) benchmark (radio tuning or destination entry); and (3) driver age. Secondary tasks performed included two methods of phone dialing (10-digit dialing  and contact selection), text messaging, destination entry and radio tuning.
Study results showed that text messaging was associated with the highest level of distraction potential. Ten-digit dialing was the second most distracting task; radio tuning had the lowest level. Although destination entry was no more demanding than radio tuning when task duration effects were eliminated with DFD metrics, it exposes drivers to more risk than radio tuning and phone tasks due to its considerably longer duration. Modest differences between phones were observed, including higher levels of driving performance degradation associated with the touch screen relative to the hard button phone for several measures. Additional analyses demonstrated that the way in which task duration is considered in the definition of metrics influenced the outcomes of statistical tests using the metrics. The results are discussed in the context of the development of guidelines for assessment of the distraction potential of tasks performed with in-vehicle information systems and portable devices.
Additional analyses were conducted to compare the DFD and Alliance Guidelines' decision criteria in a simulated compliance scenario. With the large sample size (N = 100), both protocols supported the conclusion that neither text messaging nor 10-digit dialing is suitable for combining with driving; however, when a smaller (N = 40) sample was used, the protocols led to different conclusions. Considering only the vehicle performance metrics (not the eye glance metrics), samples of 20 participants did not provide sufficient statistical power to differentiate among secondary tasks.
Driver age had significant effects on both primary and secondary task performance; younger drivers completed more secondary task trials on a given drive with relatively less primary task interference than older drivers. Tests conducted using samples with wide age ranges (25-64) required larger samples to compensate for reduced homogeneity relative to samples with narrow age ranges.
Based on these results, two issues were identified as having implications for developing guidelines to assess the distraction potential of tasks performed with in-vehicle and portable systems. The first issue pertains to the question of how to incorporate task duration into the construction and interpretation of metrics. Secondary tasks differ in duration and these differences influence the overall exposure to risk. Metrics that summarize performance over varying durations are influenced by differences in task duration. In contrast, metrics that normalize for task duration summarize task performance over equivalent time intervals and thus represent the expected magnitude of performance degradation at any point in time during which a task is performed. These approaches provide complementary information, which could be used together to characterize the total exposure to risk associated with different tasks. One approach toward integration involves using duration-controlled metrics to estimate the average level of performance degradation associated with a particular secondary task and then multiplying this estimate by the average or some specified percentile (e.g., 85th) task duration to estimate the total exposure to risk associated with performing the task once.
The finding having the most prominent implications for developing driver distraction guidelines for visual-manual interactions was that the driving simulation method of measuring distraction potential is most sensitive to differences in distraction levels of secondary tasks when performed using more than 40 test participants of homogeneous age range.
G. Principal Findings of NHTSA Driver Distraction Metric Research
Each of the research studies described above provided information which laid the foundation for the NHTSA Guidelines. The principal findings include the following:
- Visual-manual secondary tasks affected driving performance more than auditory-vocal tasks.  This could change as auditory-vocal interfaces become more prevalent and allow drivers to perform more complex secondary tasks.
- Eye-glance data contained important information for assessing the distraction effects of both auditory-vocal and visual-manual tasks. 
- The interference to driving caused by in-vehicle secondary tasks was multidimensional and no single metric could measure all effects. 
- CAMP Driver Workload Metrics project concluded that cognitive distraction played a much smaller role than visual distraction.  Again, this could change as auditory-vocal interfaces become more prevalent and allow drivers to perform more complex secondary tasks.
The research involved the development of sensitive test procedures and metrics for measuring driver distraction. Some of the conclusions drawn from the research which contributed to the basis of content in the NHTSA Guidelines include:
- Experimentation involving a fixed-based driving simulator in a laboratory environment provided better control of test conditions, particularly visibility, and less measurement error than did experimentation utilizing a test track. 
- Limited fidelity of driving simulation did not reduce the sensitivity of simulator-based metrics for detecting targeted differences between task conditions. 
- Metrics found to be sensitive to differences between visual-manual task conditions include lane-position variability (SDLP), the time required for a following vehicle to react to lead vehicle speed changes, and detection task response time. 
- Metrics found to be sensitive to differences between auditory-vocal task conditions included the time required for a following vehicle to react to lead vehicle speed changes, detection task response time, and detection task proportion of correct responses. 
- Core metrics for assessing distraction potential using driving simulator-based methods include lane-position variability, the time required for a following vehicle to react to lead vehicle speed changes, detection task response time, and the proportion of correct responses due to their increased sensitivity for detecting differences within task conditions. 
- Differences in sample size and sample construction (test participant age) have significant differences on test outcome. Sample sizes larger than 40 participants are needed for the vehicle performance metrics in order to provide adequate statistical power and avoid effects of sample composition. 
- A driving scenario involving a following task with constant lead vehicle speed seems to provide a less realistic level of driving task difficulty and may not sufficiently engage test participants in the test protocol. 
With regard to specific tasks and their treatment in the NHTSA Guidelines for visual-manual tasks, the following research findings provided key input:
- Text messaging was found to be more distracting than any other secondary task considered in this study on a number of metrics. The Alliance and DFD metrics and decision criteria both supported the conclusion that text messaging is not suitable for performance while driving. 
- Phone dialing using 10 digits was found to be only slightly less distracting than text messaging. For larger sample sizes, the Alliance and DFD metrics and decision criteria both suggested that 10-digit phone dialing is not suitable for performance while driving.  This study did not examine 7-digit phone dialing. However, NHTSA is currently performing research to examine the suitability of 7-digit phone dialing while driving.
V. Driver Distraction Prevention and Reduction Guidelines Back to Top
A. Currently Existing Driver Distraction Guidelines
On July 18, 2000, NHTSA held a public meeting to address a growing concern in the traffic safety community—driver distraction. This meeting addressed the rapid emergence of informational and entertainment devices, as well as cellular telephones. Consistent with NHTSA's regulatory authority, the Agency issued a challenge to the automotive industry—develop interface guidelines to reduce the distraction potential of emerging technologies. The Alliance of Automobile Manufacturers accepted the challenge by developing a set of “best practices” for “telematic” (communication, entertainment, information, and navigation) devices. The first version of the Alliance's Statement of Principles, Criteria and Verification Procedures on Driver Interactions with Advanced In-Vehicle Information and Communication Systems (referred to elsewhere in this document as the Alliance Guidelines), were published in December 2000. Updates to the Alliance Guidelines was published in April 22, 2002 (Version 2.0), November 19, 2003 (Version 2.1), and, the most recent version (Version 3.0), on June 26, 2006. 
The Alliance Guidelines consist of 24 principles (organized into five groups: Installation Principles, Information Presentation Principles, Principles on Interactions with Displays/Controls, System Behavior Principles, and Principles on Information about the System) that apply to each device's driver interface to ensure safe operation while driving. Each principle includes, when appropriate for that principle, a rationale, verification methods, acceptability criteria, and examples. Quoting from the Alliance Guidelines,  its principles are as follows:
Section 1: Installation Principles
Principle 1.1: The system should be located and fitted in accordance with relevant regulations, standards, and the vehicle and component manufacturers' instructions for installing the systems in vehicles.
Principle 1.2: No part of the system should obstruct the driver's field of view as defined by applicable regulations.
Principle 1.3: No part of the physical system should obstruct any vehicle controls or displays required for the driving task.
Principle 1.4: Visual displays that carry information relevant to the driving task and visually-intensive information should be positioned as close as practicable to the driver's forward line of sight.
Principle 1.5: Visual displays should be designed and installed to reduce or minimize glare and reflections.
Section 2: Information Presentation Principles
Principle 2.1: Systems with visual displays should be designed such that the driver can complete the desired task with sequential glances that are brief enough not to adversely affect driving.
Principle 2.2: Where appropriate, internationally agreed upon standards or recognized industry practice relating to legibility, icons, symbols, words, acronyms, or abbreviations should be used. Where no standards exist, relevant design guidelines or empirical data should be used.
Principle 2.3: Available information relevant to the driving task should be timely and accurate under routine driving conditions
Principle 2.4: The system should not produce uncontrollable sound levels liable to mask warnings from within the vehicle or outside or to cause distraction or irritation.
Section 3: Principles on Interactions with Displays/Controls
Principle 3.1: The system should allow the driver to leave at least one hand on the steering control.
Principle 3.2: Speech-based communication systems should include provision for hands-free speaking and listening. Starting, ending, or interrupting a dialog, however, may be done manually. A hands-free provision should not require preparation by the driver that violates any other principle while the vehicle is in motion.
Principle 3.3: The system should not require uninterruptible sequences of manual/visual interactions. The driver should be able to resume an operator-interrupted sequence of manual/visual interactions with the system at the point of interruption or at another logical point in the sequence.
Principle 3.4: In general (but with specific exceptions) the driver should be able to control the pace of interaction with the system. The system should not require the driver to make time-critical responses when providing input to the system.
Principle 3.5: The system's response (e.g. feedback, confirmation) following driver input should be timely and clearly perceptible.
Principle 3.6: Systems providing non-safety-related dynamic (i.e. moving spatially) visual information should be capable of a means by which that information is not provided to the driver.
Section 4: System Behavior Principles
Principle 4.1: Visual information not related to driving that is likely to distract the driver significantly (e.g., video and continuously moving images and automatically scrolling text) should be disabled while the vehicle is in motion or should be only presented in such a way that the driver cannot see it while the vehicle is in motion.
Principle 4.2(a): System functions not intended to be used by the driver while driving should be made inaccessible for the purpose of driver interaction while the vehicle is in motion.
Principle 4.2(b): The system should clearly distinguish between those aspects of the system, which are intended for use by the driver while driving, and those aspects (e.g. specific functions, menus, etc) that are not intended to be used while driving.
Principle 4.3: Information about current status, and any detected malfunction, within the system that is likely to have an adverse impact on safety should be presented to the driver.
Section 5: Principles on Information about the System
Principle 5.1: The system should have adequate instructions for the driver covering proper use and safety-relevant aspects of installation and maintenance.
Principle 5.2: Safety instructions should be correct and simple.
Principle 5.3: System instructions should be in a language or form designed to be understood by drivers in accordance with mandated or accepted regional practice.
Principle 5.4: The instructions should distinguish clearly between those aspects of the system that are intended for use by the driver while driving, and those aspects (e.g. specific functions, menus, etc.) that are not intended to be used while driving.
Principle 5.5: Product information should make it clear if special skills are required to use the system or if the product is unsuitable for particular users.
Principle 5.6: Representations of system use (e.g. descriptions, photographs, and sketches) provided to the customer with the system should neither create unrealistic expectations on the part of potential users, nor encourage unsafe or illegal use.
The Alliance Guidelines provide a comprehensive set of recommendations designed to limit visual-manual distraction while driving. The document includes relevant definitions, human factors principles for good device driver-interface design, methods for verifying compliance with the principles, and a number of examples. These Alliance Guidelines serves as an excellent foundation for the development of the NHTSA Guidelines.
In addition to the Alliance Guidelines, numerous other standards and guidelines documents have been developed. A summary of these is contained in the SAE paper “Driver Interface/HMI Standards to Minimize Driver Distraction/Overload.”  The two other sets of these guidelines that most directly deal with driver distraction (in addition to the Alliance Guidelines) were:
- Commission Recommendation of 26 May 2008 on Safe and Efficient In-Vehicle Information and Communication Systems; Update of the European Statement of Principles on Human-Machine Interface (referred to as the “European Guidelines”). 
- The Japan Automobile Manufacturers Association Guidelines for In-vehicle Display Systems—Version 3.0 (referred to as the “JAMA Guidelines”). 
The European Guidelines consist of 34 principles that each in-vehicle device's driver interface should meet to ensure safe operation while driving, as well as 16 safety recommendations for drivers, employers, advertisers, and personnel working for vehicle-for-hire operations. Driver interface principles are grouped into the following areas: Overall Design Principles, Installation Principles, Information Principles, Interactions with Controls and Displays Principles, System Behavior Principles, and Information about the System Principles, most of which are similar to the corresponding principles in the Alliance Guidelines. The principles present in the European Guidelines that are not present in the Alliance Guidelines are typically understood in the latter and do not have verification methods given in the former. For example, the first European Guidelines principle is:
The system supports the driver and does not give rise to potentially hazardous behavior by the driver or other road users. 
While this principle is not explicitly written in the Alliance Guidelines, reading them clearly shows that this principle is the underlying one for all of the Alliance Guidelines.
Unlike the Alliance Guidelines, the European Guidelines do not prescribe testing methods and acceptance criteria for determining whether a task can safely be performed by the driver while a vehicle is in motion. For example, one very important Alliance Guidelines principle, Principle 2.1, is:
Systems with visual displays should be designed such that the driver can complete the desired task with sequential glances that are brief enough not to adversely affect driving. 
The Alliance Guidelines then follow this statement with many pages describing how to verify that a device's interface meets this principle. In contrast, the corresponding European Guidelines principle reads:
Visually displayed information presented at any one time by the system should be designed in such a way that the driver is able to assimilate the relevant information with a few glances which are brief enough not to adversely affect driving. 
However, the European Guidelines limit statements about the verification process to:
Compare design alternatives for the presentation of information: the number and duration of glances needed to detect and acquire relevant information presented at any one time should be minimized. 
The JAMA Guidelines consist of four basic principles and 25 specific requirements that apply to each device's driver interface to ensure safe operation while driving. Specific requirements are grouped into the following areas: Installation of Display Systems, Functions of Display Systems, Display System Operation While Vehicle in Motion, and Presentation of Information to Users. Additionally, there are three annexes: Display Monitor Location, Content and Display of Visual Information While Vehicle in Motion, and Operation of Display Monitors While Vehicle in Motion, as well as one appendix: Operation of Display Monitors While Vehicle in Motion.
Approximately one-half of the specific requirements in the JAMA Guidelines are essentially identical to the corresponding principles in the Alliance and European Guidelines.
Like the Alliance Guidelines, the JAMA Guidelines prescribe acceptance criteria for determining whether a task can safely be performed by the driver while a vehicle is in motion. Based on the specified acceptance criteria, the JAMA Guidelines imply the use of the same testing methods (the JAMA Guidelines do not actually specify testing methods) as are contained in the Alliance Guideline's Alternative A verification options: Eye Tracker Measurement, Video Recording of Test Participant's Eyes/Face, and Testing using Occlusion. However, the JAMA acceptance criteria are more constraining than those found in the Alliance Guidelines. The JAMA Guidelines limit the maximum driver total glance time while performing a task (JAMA uses the same definition for task as is used in the Alliance Guidelines) to 8.0 seconds or 7.5 seconds if occlusion is used (compare to the Alliance Guidelines limits of 20.0 seconds for maximum driver total glance time or 15.0 seconds for occlusion).
The JAMA Guidelines also contain a recommended limit on the amount of dynamic test that can be displayed to the driver at one time. As the JAMA Guidelines state:
The number of letters (e.g., characters, kana, alphabets) displayed at a time shall not exceed 31,  provided that a number such as “120” or a unit such as km/h” is deemed to be a single letter irrespective of the number of digits. Punctuation marks are not included in the count of letters. 
The JAMA Guidelines are far shorter, and, as a result, far less detailed than either the Alliance or European Guidelines.
Of the various driver distraction prevention and reduction guidelines that were reviewed, NHTSA has decided that the current version of the Alliance Guidelines serves as the best basis for the development of the NHTSA Guidelines. They are the most complete of the three guideline sets considered and contain far more information about verification procedures than do the European or JAMA Guidelines. There are only a few contradictions between the three sets of guidelines, with the principal one being the JAMA Guidelines previously discussed prohibition on performing non-driving related tasks while in motion.
The Alliance and European Guidelines are quite similar; a device that meets one set of these guidelines will meet the other. The Japanese Guidelines are more restrictive—they do not allow quite a number of devices to function whenever the vehicle is in motion. As a result, a vehicle that strictly follows the JAMA Guidelines should meet all of the recommendations of both the Alliance and European Guidelines but not necessarily vice-versa.
When there are items contained in either the European or JAMA Guidelines that are not in the Alliance Guidelines, NHTSA has carefully considered them and included them in the NHTSA Guidelines when we agree with them (e.g., the 30 character limit in the NHTSA Guidelines on the amount of text that may be read comes from the JAMA Guidelines).
As a convenience to readers, NHTSA has placed copies of the Alliance, European, and JAMA Guidelines into the distraction docket. 
B. Why NHTSA Is Issuing Its Own Guidelines for Limiting and Reducing Driver Distraction
NHTSA has decided to issue its own guidelines for limiting and reducing driver distraction associated with the use of in-vehicle electronic devices while driving. Voluntary guidelines developed by others in the past have been instrumental in the development of these NHTSA Guidelines. The NHTSA Guidelines are being issued for the following reasons:
- So as to have guidelines available for all passenger cars, multipurpose passenger vehicles, and trucks and buses with a Gross Vehicle Weight Rating (GVWR) of not more than 10,000 pounds.
- So as to have guidelines applicable to all communications, entertainment, information, and navigation devices installed in vehicles as original equipment.
- So as to incorporate the latest driver distraction research into the guidelines. There has been much research on driver distraction in the five years since the Alliance Guidelines were last updated; NHTSA believes that it is valuable to incorporate the results of this recent research into guidelines that serve to reduce or prevent driver distraction prevention.
- Per the Highway Safety Act of 1970, NHTSA is responsible for reducing deaths, injuries and economic losses resulting from motor vehicle crashes; in short, NHTSA is responsible for vehicle safety. While manufacturers also have a strong interest in safety, they are also influenced by other factors, such as market forces. Therefore, the NHTSA Guidelines will focus solely on safety and the safety impact of final (i.e., consumer-ready) products. In contrast, other guidelines focus more on the design process, which involves consideration of factors in addition to safety, and include metrics that can be used on prototype designs.
- NHTSA has identified some aspects of the current Alliance Guidelines that are loosely specified or provide multiple compliance assessment options that may correspond to different levels of associated safety. NHTSA would like to specify a test procedure that is straight-forward, clearly defined, and well-substantiated in order to aid the voluntary adoption of its NHTSA Guidelines. Minimizing the opportunity for variability in carrying out the test procedure will ensure that manufacturers would be able to easily and consistently implement the NHTSA Guidelines across their light vehicle fleets.
Before undertaking this guideline effort, NHTSA met with several manufacturers in 2010 to determine how they had implemented the Alliance Guidelines. During these meetings, NHTSA learned that implementation varies across, and sometimes within, manufacturers. This information has been useful to NHTSA to attain a better understanding of the practical considerations and constraints facing manufacturers when developing vehicle technologies. This information has been taken under consideration by NHTSA while drafting the new NHTSA Guidelines.
The NHTSA Guidelines, while adopting much of the content of the Alliance Guidelines, incorporate a number of changes in an effort to further enhance driving safety, to enhance guideline usability, to improve implementation consistency, and to incorporate the latest driver distraction research findings. The proposed NHTSA Guidelines and their rationales, including the rationale for departures from the Alliance Guidelines, are discussed in detail in later portions of this notice.
C. First Phase of NHTSA's Driver Distraction Guidelines Focuses on Original Equipment Devices With Visual-Manual Driver Interfaces
As discussed in NHTSA's Driver Distraction Program, NHTSA's intent is to “develop voluntary guidelines for minimizing the distraction potential of in-vehicle and portable devices.” Electronic devices in a motor vehicle can divided into three broad classes, depending upon their origin. These devices may have been built into a vehicle when it is manufactured (i.e., original equipment devices), installed in a vehicle after it has been built (i.e., aftermarket devices), or brought into a vehicle (portable devices). The current notice only contains voluntary NHTSA Guidelines for visual-manual interactions associated with original equipment devices. Portable devices will be addressed by Phase 2 of the NHTSA Guidelines. These and the remaining phases of the NHTSA Guidelines are outlined in Table 2.
As noted earlier, drivers perform tasks using an in-vehicle electronic device by interacting with the device through its driver interface. The driver interfaces of these devices can be designed to accommodate interactions that are visual-manual, auditory-vocal, or a combination of the two.
The goal of the NHTSA Guidelines is to discourage the design of in-vehicle device interfaces that do not minimize driver distraction associated with secondary task performance. The NHTSA Guidelines specify criteria and a test method for assessing whether a secondary task performed using an in-vehicle device may be suitable for performance while driving, due to its minimal impact on driving performance and, therefore, safety. The NHTSA Guidelines also seek to identify secondary tasks that interfere with a driver's ability to safely control their vehicle and to categorize those tasks as ones that are not suitable for performance by the driver while driving.
For each of the three possible origins of in-vehicle electronic devices, both visual-manual and auditory-vocal interaction modes may be possible. Table 2 indicates the order in which NHTSA plans to develop its NHTSA Guidelines to address the different device origins and interfaces.
|Type of interaction||Origin of device|
|Visual-Manual||NHTSA Driver Distraction Guidelines, Phase 1||NHTSA Driver Distraction Guidelines, Phase 2||NHTSA Driver Distraction Guidelines, Phase 2.|
|Auditory-Vocal||NHTSA Driver Distraction Guidelines, Phase 3||NHTSA Driver Distraction Guidelines, Phase 3||NHTSA Driver Distraction Guidelines, Phase 3.|
This notice proposes Phase 1 of the NHTSA Driver Distraction Guidelines. NHTSA plans to issue Phase 2 (aftermarket and portable devices) of its NHTSA Guidelines in 2013 and Phase 3 (auditory-vocal interfaces) in 2014. Our NHTSA Guidelines are being developed in these phases because:
- While some international and voluntary consensus standards exist that relate to visual-manual interfaces for in-vehicle devices, no similar standards for devices with auditory-vocal interfaces exist. Auditory-vocal interfaces are newer than are visual-manual interfaces; as a consequence less research has been performed on driver distraction while using auditory-vocal interfaces. Research is needed on such subjects as how to best measure the level of driver distraction induced when auditory-vocal interfaces are used. Based on this shortage of research, NHTSA intends to delay the extension of its NHTSA Guidelines to cover auditory-vocal interfaces until Phase 3 of guideline development.
- From naturalistic driving research, the secondary tasks with the highest risk odds ratios tend to be primarily visual-manual in nature with only a relatively small cognitive component. Of course, every secondary task results in some cognitive load; however, tasks such as Reaching for a Moving Object or Eating require that the driver's eyes and hands be used to perform non-driving tasks but do not require a lot of thought. It is not until the ninth highest risk odds ratio in Figure 1; Talking/Listening to a Hand-Held Device that a secondary task appears that is heavily cognitive in nature.  Furthermore, this secondary task's risk odds ratio is not statistically significantly different from 1.00 at the 95 percent confidence level. In fact, there are no secondary tasks in Figure 1 that have risk odds ratios which are statistically significantly greater than 1.00 that are primarily cognitive in nature.
- There may be special challenges associated with guidelines for both aftermarket and portable devices. Given that for some device types the only substantial difference between an integrated and a portable version of the device will be the device location (fixed or variable), most of the NHTSA visual-manual Driver Distraction Guideline criteria are expected to also be appropriate for aftermarket and portable devices with visual-manual driver interfaces. However, NHTSA thinks that additional research is necessary to determine if there are other considerations for guidelines for aftermarket and portable devices. Therefore, NHTSA intends to implement the extension of its NHTSA Guidelines to cover aftermarket and portable devices in Phase 2 of guideline development.
D. Past NHTSA Actions on Driver Distraction
Before this notice, NHTSA had published one Federal Register notice that was related to driver distraction. On June 3, 2008, NHTSA denied  a petition from the Center for Auto Safety requesting that NHTSA do the following:
1. Issue a Notice of Proposed Rulemaking (NPRM) to require that any personal communication systems integrated into a vehicle, including cellular phones and text messaging systems, be inoperative when the transmission shift lever is in a forward or reverse gear.
2. Issue an Advance Notice of Proposed Rulemaking (ANPRM) to consider requiring that other integrated telematic systems in vehicles that significantly increase crash rates be inoperative when the transmission shift lever is in a forward or reverse gear.
3. Increase efforts to support state programs to limit cell phone use by drivers in moving vehicles in the same manner that it supports state programs against drunk driving.
Part of NHTSA's rationale for denying the Center for Auto Safety petition was, as stated in the Federal Register notice, the concern that:
If integrated cell phones and other telematic devices were required to be inoperative, drivers could instead use portable devices such as their regular cell phones. 
NHTSA remains concerned about the possibility of drivers increasing their use of portable devices due to restrictions being placed on integrated devices. Based on this concern, NHTSA considers it essential that guidelines for aftermarket and portable devices be developed as rapidly as feasible following the development of NHTSA Guidelines for original equipment devices. As shown in Table 2 and explained in the discussion following this table, the development of NHTSA Guidelines for aftermarket and portable visual-manual device interfaces (Phase 2) is planned to begin immediately following the completion of the original equipment visual-manual NHTSA Guidelines (Phase 1).
E. Challenges Relating to the Development of Interface Guidelines To Minimize Driver Distraction
Developing guidelines for device driver interfaces that minimize distraction and its impact on driving performance is complicated. Research is ongoing to identify the best methods and metrics by which to measure the effects of distraction on driving performance. Even though research on this topic has not been completed, NHTSA thinks it important to be proactive and provide guidance on how manufacturers may limit the range and complexity of in-vehicle device tasks that may be considered in the future so as to ensure the safety of drivers and fellow road users. Therefore, NHTSA presents in this notice its current “best” proposal based on information currently available.
The challenges involved in developing driver distraction guidelines and assessing whether covered devices meet associated criteria are many and non-trivial. These challenges include:
1. Ensuring that criteria that device tasks should meet are rigorously developed, validated, and substantiated by experimental data.
2. Developing Guideline criteria that are generalized to all device types covered by these NHTSA Guidelines, including a wide range of existing devices and tasks as well as ones that may appear in future vehicles but have not yet been conceived.
3. Identifying sensitive metrics for measuring distraction and the most appropriate characteristics of the sample population used to assess the metrics.
4. Developing a test scenario for use in assessing the degree to which in-vehicle device tasks meet Guideline criteria that simulates the demand of actual driving under suitable and “representative” conditions.
5. Developing a repeatable and well-defined test protocol for use in assessing the degree to which in-vehicle device tasks meet Guideline criteria that implement the chosen driving scenario.
6. Formulating a tightly specified task definition to ensure that similar tasks are assessed for their ability to meet Guideline criteria in a similar manner by all relevant manufacturers.
7. Establishing criteria for the sample of experimental subjects to be tested using the test protocol (i.e., number of test participants; test participant age ranges, experience, etc.).
8. Assessing whether minimizing total eyes-off-road time spent on a given secondary task actually results in an overall reduction in the total amount of eyes-off-road time spent on all secondary tasks, especially as the number of secondary tasks multiply with the introduction of more and more entertainment, communication and information devices, and capabilities.
Each of these challenges is elaborated upon in the following paragraphs.
1. The Guideline and task performance criteria that devices should meet need to be rigorously developed, valid, and substantiated by experimental data. While driver distraction is a topic for which most of the general public has opinions, decisions relating to what tasks a driver should be free to perform while driving should be made based on objective data. Having a data-based means of substantiating distraction guidelines provides a firm foundation to guarantee that measurable safety improvements are actually achieved.
2. Developing appropriate Guideline criteria for the broad range of current and future device task types and input methods is highly challenging. To date, a variety of manual means through which drivers can make control inputs to in-vehicle systems have been used. NHTSA Guidelines for systems with visual-manual interaction means should cover all types of traditional input controls, touch screens, and means of providing feedback to the driver. Beyond control input method, the types of tasks available vary and the extent of electronic device related tasks that may become available in future vehicles cannot be known at this time. For these reasons, establishing guidelines that will remain relevant in the long-term is a challenging issue.
3. Various metrics for characterizing distraction's impact on driving performance have been developed, but are still being debated within the research community and industry. Metric sensitivity and the relationship between the metrics and crash risk are topics of much contention. Some metrics require testing large numbers of test participants in order to achieve sufficient statistical power to allow significant effects to be observed, if they exist. Acceptance criteria need to be selected and justified based on safety data.
4. A test scenario that simulates the demands of actual driving under suitable and “representative” conditions needs to be defined in order to provide a baseline for use in measuring the impact of distracted driving. It should be insensitive to the dynamics of the vehicles being tested so as to minimize the need for complex and expensive vehicle characterization testing.
The amount of interference created by secondary task performance while driving is dependent on the complexity of the driving scenario in which the secondary task is performed. Drivers will have more spare attentional capacity that may be used to perform secondary tasks in less complex traffic conditions than they would in more complex traffic conditions. Therefore, secondary task performance would be expected to impact driving performance less in a low complexity driving situation than in a high complexity one. Choosing the most appropriate level of driving scenario complexity for assessment of distraction effects is difficult and important.
5. A test procedure must be developed to be able to assess adherence to the driver distraction guidelines criteria. While typical compliance testing measures the effects of a known magnitude and type of stimulus on a specific vehicle design's motion or structural integrity, a test of driver distraction measures the effects of a stimulus, the magnitude of which is difficult to quantify, on the ability of a non-standardized and variable system (i.e., the driver) to control a vehicle safely. Given that the population of drivers varies widely in a number of aspects including driving skill, multi-tasking ability, attentional focus capacity, and propensity to perform non-driving tasks while driving, the sample of drivers needed for a test to determine adherence to the NHTSA Guidelines would need to be much larger than the sample size of one typically associated with a vehicle performance compliance test. Appropriate data reduction methods and tools also must be developed.
6. In order to have a standardized test for measuring the impact of secondary task performance on driving performance and safety, the test criteria must be well-specified. In particular, a clear definition of a “task” must be asserted to specify the series of driver actions needed to perform a secondary task that should be assessed for adherence to the NHTSA Guidelines' criteria. Unclear task specifications can result in inconsistent guideline adherence test performance throughout the industry. While the definition of task used in the Alliance Guidelines is short and conceptually clear, it can be difficult to determine for real devices whether something is one task or several. This is particularly challenging to do for devices and tasks that have not yet been developed.
7. Characteristics of the sample of test participants to be subjected to the test protocol (number of test participants; test participant criteria including age, experience, conflicts of interest, etc.) need to be identified. NHTSA is particularly worried about prior test participant experience with the devices that are being evaluated. Devices are frequently far more difficult to use (and hence, distracting) when drivers are not familiar with them. However, the vast majority of device usage is by drivers who use a device daily and are highly familiar with their operation.
8. It must be determined whether minimizing the total eyes-off-road time spent on a given secondary task actually results in an overall reduction in the total amount of eyes-off-road time spent on all secondary tasks. This is particularly important as the number of non-driving secondary tasks seemingly multiplies as more entertainment, communication and information devices, and capabilities are introduced into vehicles. (Are the number and variety of secondary tasks in fact multiplying or does it just seem that way?) Many people have speculated that making it safer for drivers to perform secondary tasks while driving will encourage drivers to perform more secondary tasks while driving. This is another application of risk homeostasis theory; people have an acceptable level of risk that they are comfortable with and they compensate for reductions in risk by taking on additional risks so as to maintain a relatively constant level of risk.
There is undoubtedly a certain amount of truth to risk homeostasis theory with regard to driving safety. For example, over the last 50 years, numerous safety improvements have been implemented in motor vehicles. Risk homeostasis theory predicts that drivers would drive more dangerously so as to maintain their overall acceptable level of risk. One way to do this is by driving faster. There is some evidence that this has happened. Speed limits have been increased. While drivers used to speed when the national speed limit was 55 mph, they still speed today when interstate highway speed limits have been increased to 65 to 75 mph. However, there is a clearly decreasing trend in the number of motor vehicle fatalities, especially when they are normalized by the number of vehicle miles traveled.
What seems to have happened in the past is that safety improvements have been partially, but not totally, offset by riskier driving behavior (frequently by increases in driving speed). However, substantial improvement in safety has remained, even after the changes in driver behavior. True risk homeostasis did not occur, but we did see behavioral adaptation as drivers partially compensated for the decrease in risk.
NHTSA anticipates that similar changes in driver behavior may be seen due to these NHTSA Guidelines. Some portion of the otherwise expected improvement in safety and reduction in driver workload associated with task performance may be used by drivers to perform more secondary tasks. However, there should also be an improvement in overall driving safety.
While NHTSA's primary focus is driving safety, other things are also important to drivers. Drivers, like any other category of people, will seek to have their personal needs met. Drivers are not forced to perform additional secondary tasks just because they have a vehicle designed for safe in-vehicle secondary task performance. Drivers perform these additional secondary tasks to meet their own needs. Even though some portion of the expected improvement in safety may be negated by the performance of more secondary tasks, the overall quality of life will be improved for drivers and other road users.
VI. Justification for Specific Portions of NHTSA Guidelines for Reducing Driver Distraction During Interactions With In-Vehicle Systems Back to Top
A. Intended Vehicle Types
These proposed NHTSA Guidelines are appropriate for all passenger cars, multipurpose passenger vehicles, and trucks and buses with a GVWR of not more than 10,000 pounds. These are what NHTSA has traditionally called “light vehicles.” This category of vehicles has been the primary focus of NHTSA's past driver distraction research. Additionally, light vehicles have been a major platform for the push to incorporate built-in advanced technology, entertainment, and communications functions into vehicles. Focusing on this vehicle category serves as a step towards ensuring that the increasing features being offered in all vehicles do not produce an overwhelmingly distracting in-vehicle environment for the driver that can degrade safety. For these reasons, NHTSA has focused its distraction research on light vehicles. While much of what NHTSA has learned about light vehicle driver distraction undoubtedly applies to other vehicle types, additional research would be needed to assess whether all aspects of these NHTSA Guidelines are appropriate for application to those vehicle types.
B. Existing Alliance Guidelines Provide a Starting Point
The NHTSA Guidelines derive in part from the document “Statement of Principles, Criteria, and Verification Procedures on Driver Interactions with Advanced In-Vehicle Information and Communication Systems including 2006 Updated Sections” that was developed by the Alliance of Automobile Manufacturer's Driver-Focus Working Group (frequently referred to as the Alliance Guidelines).  Portions of the Alliance Guidelines have been carried over to the NHTSA Guidelines without changes. When the NHTSA Guidelines differ from the Alliance Guidelines, it is either due to recent research that has been performed since the development of the Alliance Guidelines or because NHTSA believes that the changes made will increase the safety of the motoring public.
A number of the Alliance Guideline principles are not included in the NHTSA Guidelines. While NHTSA generally agrees with the excluded principles, NHTSA thinks that these principles are not appropriate to include in these NHTSA Guidelines.
The excluded principles, and their reasons for exclusion, are as follows:
- Principle 1.1: The system should be located and fitted in accordance with relevant regulations, standards, and the vehicle and component manufacturers' instructions for installing the systems in vehicles. 
NHTSA assumes that vehicle manufacturers will follow this principle when deciding where to locate devices within their vehicles. However, verification by NHTSA that devices meet this principle is difficult. The Alliance Guidelines verification section for this principle does not offer much guidance; it merely states:
Design to conform and validate by appropriate means as may be specified by relevant standards or regulations or manufacturer-specific instruction. 
As discussed above, NHTSA intends to monitor whether vehicles meet these NHTSA Guidelines to help determine their effectiveness and sufficiency. Accordingly, the NHTSA Guidelines do not include principles for which there is no reasonable method for NHTSA to assess Guideline adherence. It is hard for NHTSA to do this, at least for some devices, without having access to information known to the manufacturer but not necessarily to NHTSA. For these reasons, we do not believe it is feasible for NHTSA to develop the methods needed to monitor adherence to this principle.
- Principle 1.5: Visual displays should be designed and installed to reduce or minimize glare and reflections. 
Vehicle manufacturers report that they follow this principle when installing when deciding where to locate devices within their vehicles. Additionally, verification by NHTSA that devices meet this principle is difficult. The Alliance Guidelines verification section for this principle again does not offer much guidance; it merely states:
Verification should be done by appropriate means (e.g., analysis, inspection, demonstration, or test). 
Furthermore, glare and reflections on device interfaces only indirectly contribute to driver distraction (and thereby affect safety). Finally, glare and reflection reduction and minimization is a complex problem that is best left to the vehicle designer. For all of these reasons, it does not seem feasible for NHTSA at this time to develop the complicated methods needed to monitor adherence to this principle.
- Principle 5.1: The system should have adequate instructions for the driver covering proper use and safety-relevant aspects of installation and maintenance. 
- Principle 5.2: Safety instructions should be cor